TULSA — Oklahoma’s Health Department says the cost of tests for thousands of patients of a Tulsa dentist being investigated for keeping unsanitary offices is nearing $700,000.

So far, 3,568 of Dr. W. Scott Harrington’s 7,000 patients have had blood drawn at county health departments across the state. Each test costs about $195.

State Health Department spokeswoman Leslea Bennett-Webb says the costs associated with the investigation are sure to rise, as followup tests, patient notification and time needed for disease investigations in patients who test positive have yet to be tallied.

Since testing began last month, 65 of Harrington’s patients have tested positive for hepatitis C. Health officials caution it would be highly unusual for them to have contracted the illnesses at his clinics.